HDAC9 and cancer: To date, the U.S. Food and Drug Administration (FDA) has approved four HDAC inhibitors to be used as a monotherapy to treat several cancers, including Vorinostat (SAHA) [20], Romidepsin (FK228) [21], and Belinostat (PXD-101) [22] for treating cutaneous T-cell lymphoma (CTCL) or peripheral T cell lymphoma (PTCL) and Panbinostat (LBH-589) [23] for the treatment of multiple myeloma.